U.S. Pat. Nos. 4,773,485, 4,834,188, 5,127,479, 5,697,450, 5,871,057 and 6,044,913, each assigned to the assignee of the present invention, disclose systems for extinguishing fires which occur on residential cook stoves, fryers and ranges. U.S. Pat. No. 6,044,913 is specifically incorporated in this application by reference in its entirety. While the systems disclosed in these patents have gained wide acceptance and function effectively to extinguish fires on residential cook stoves and ranges and fryers, these patents rely on an array of heat sensing elements coupled to one another with cables strung around the internal periphery of range hoods. Since these systems require at least some skill in mechanical assembly and require adjustments in cable length, they are systems which are somewhat difficult for the average home owner to install. Moreover, these systems are relatively expensive.
Attempts have been made to develop electronic systems which do not have the difficulties of cable systems. U.S. Pat. Nos. 4,830,116 and 4,887,674 are exemplary of such systems, but the systems disclosed in these patents have not been commercialized. Other electronic systems are exemplified by U.S. Pat. Nos. 5,186,260 and 5,207,276; however, these systems rely on twisted insulated conductors which limit alarm signals upon the insulation melting. These are irreversible systems which are also subject to degradation over time. In addition, prior art arrangements are not easy to install and require drilling, measuring, screwing and bolting, which procedures tend to discourage their installation.
In view of the aforementioned considerations, there is a need for fire extinguishing systems, suitable for commercial and residential cook stoves, fryers and ranges, as well as other heating and heated devices, which are very easy to install and less expensive than the aforementioned, prior art systems.
Current fire extinguishing systems are hardwired to avoid grounding difficulties which cause unnecessary shut-off of electricity and gas due to the presence of sonically triggered alarm systems, thus limiting the systems to situations where only hardwiring can be utilized. Consequently, fire protections systems as disclosed in U.S. Pat. No. 6,044,913 are not conveniently installable in all situations. Accordingly, there is need of an arrangement that allows use of acoustically triggered shut-off systems. Moreover, there is a need for a way to conveniently incorporate add-on features with cook stove fire extinguishing systems generally configured as present commercially available systems.